The invention relates to a process for selective removal of brazing compound from underlying assemblies and, more particularly, to a process for selective removal of a nickel alloy brazing composition from a nickel-base alloy component.
Metal components are often joined by brazing. Brazing compounds have lower melting points than the materials to be joined. When a metal assembly to be joined is heated with brazing compound near the joint, the brazing compound will melt and flow into the joint under capillary action.
The repair of brazed assemblies frequently requires the removal of brazing compound so that the joined components can be separated. Conventional chemical processes for braze removal from gas turbine engine stators can require 120 hours or longer of exposure to aggressive chemical solutions at high temperature (200xc2x0 F.) under continuous ultrasonic agitation. This process requires the use of complex and non-recyclable stripping solutions, and frequently produces detrimental etching of the components.
It is clear that the need remains for an improved selective process for removing alloy brazing compositions from nickel-base alloy components without using aggressive stripping solutions and the like so as to provide a more environmentally friendly process.
It is therefore the primary object of the present invention to provide such a process.
It is a further object of the invention to provide such a process wherein the materials used can be recycled so as to reduce environmental impact and cost as well.
Other objects and advantages will appear hereinbelow.
In accordance with the present invention, the foregoing objects and advantages have been readily attained.
In accordance with the present invention, a process is provided which comprises the steps of providing a brazed assembly comprising nickel-base alloy components joined by nickel alloy brazing composition; immersing said assembly in an electrolyte; and applying a potential across said electrolyte at a magnitude wherein said nickel-base alloy components are electrochemically passive and said nickel alloy brazing composition dissolves whereby said brazing composition is removed from said components.